Magnesium base alloy



Patented Dec. 11, 1934 UNITED STATES MAGNESIUM BASE ALLOY John A. Gann, Midland, Mich, assignor to The Dow Chemical Company, corporation of Michigan Midland, Mich, a

No Drawing. Application August 9, 1933, Serial No. 684,398

4 Claims.

The invention relates to magnesium base alloys. by which is meant alloys containing 50 per cent or more of magnesium, and is more partic- 5 ularly concerned with such alloys containing both tin and manganese.

The binary alloys of magnesium and manganese and of magnesium and tin are known, being described in United States Patents Nos. 1,377,374 and 1,680,262, respectively, but these alloys are not well adapted to be worked into intricate shapes by such operations as forging and the like. I have found that the ternary magnesium base alloys containing both tin and manganese are superior in many respects to the parent binary alloys, may be forged readily and possess good resistance to corrosion. Such alloys, therefore, are useful for the production of wrought articles, as well as for making castings and extruded forms, where resistance to corrosion together with a high degree of strength are desired. The invention, then, consists of the magnesium base alloys containing both tin and manganese hereinafter more fully described and particularly pointed out in the claims.

In general the proportion of tin may be from 0.1 to 15 per cent and that of manganese from 0.1 to 5 percent or preferably 0.5 to 5 per cent. In specific instances certain proportions of these metals within the ranges stated are preferable for particular purposes. For example, for the production of castings from 3 to 12 per cent of tin and from 0.2 to 2 per cent of manganese may be used, while alloys best adapted for forging, extruding, and the like may contain from 1 to 8 per cent of tin and from 0.5 to 1.5 per cent of manganese.

In the following table, examples are given illustrating the properties of my new alloy which were obtained by tests upon extruded samples, 40 together with the properties of extruded specimens of the parent binary alloys.

Table 45 T 'l t gth '1' Id t gtl l cent sun as ten re s ten 1 e onga Nomi?! composmon lbs/sq. in. lbs/sq. m. tion in 2 inches Bilr sary alloy: 10 t 12 n o 50 Bazfnce Mg 00,000 to 32,000 13,000 to 18,000

. n Big noe M 43000 23000 Ternary alloy:

1-8% Sn.-... 1.5 0 Mn... 40,000 to 45,000 27,000 to 33,000 8 to 12 5 Ba ance Mg Yield strength is defined as the load in lbs/sq. in. at which the stress-strain curve deviates 0.1% elongation from the modulus line.

I have found that these new alloys may be plastic-ally deformed by such operations as hammering, pressing, rolling, and the like without fracturing the same at a temperature between 600 and 900 F. to produce wrought articles the resistance to corrosion of which is very much greater than the magnesium-alurninum-manganese alloys, now the most widely used of the commercial magnesium base alloys.

Although the aforementioned magnesium base alloys containing both tin and manganese are entirely satisfactory for the purposes described, it may be desirable in some instances to add other alloying metals to increase their strength still further without materially decreasing their malleability, resistance to corrosion, and other valuable properties. To obtain such increase of strength, from 1 to 5 per cent of either aluminum, cadmium or zinc may be added.

The alloys described may be prepared by the known methods of melting and alloying metals with magnesium, such as adding the respective alloying metals to a bath of molten magnesium protected from oxidation by a covering of fluid flux.

Among the advantages of my alloys are their lightness, high strength. ability to resist corrosion, and to withstand plastic deformation without cracking.

This application is a continuation in part of a prior application Serial No. 583,138, filed December 24, 1931. of which the above applicant is one 'of the joint inventors.

Other modes of applying the principle of my invention may be employed instead of those explained, change being made as regards the proportions of the alloying metals herein disclosed, provided the metals and the proportions thereof stated by any of the following claims or the equivalent of such stated metals be employed.

I therefore particularly point out and distinctly claim as my invention:-

1. A magnesium base alloy containing from 0.1 to 15 per cent of tin and from 0.1 to 5 per cent of manganese.

2. A magnesium base alloy containing from 0.1 to 15 per cent of tin and from 0.5 to 5 per cent of manganese.

3. A magnesium base alloy containing from 3 to 12 per cent of tin and from 0.2 to 2 per cent of manganese.

4. A magnesium base alloy containing from 1 to 8 per cent of tin and from 0.5 to 1.5 per cent of manganese.

JOHN A. GANN. 

